This invention is directed to disposable sheaths for medical examining devices that are inserted into body cavities and more particularly to a disposable sheath for use with an endoscope.
Reusable medical devices, especially those which are inserted into cavities of the body such as endoscopes, must be in a sterile condition before each use. Procedures for sterilizing reusable medical devices can be relatively time consuming and expensive. In addition, there is also a likelihood that the sterility of a reusable medical device will be compromised between the time sterilization is performed and the time the device is used, especially if there is a relatively long time lapse between sterilization and use. Furthermore, in many instances it is inconvenient to sterilize a medical device just before it will be used.
It is common practice with some known reusable medical devices to provide a disposable sterile sheath as an alternative to sterilizing the device before each use. The disposable sheath covers a predetermined portion of the medical device functioning as a sterile barrier between the individual being examined and the medical device used for such examination. Thus the medical device can be conveniently and repeatedly reused without being in a sterile condition for each use.
For example, disposable sheaths are used on thermometers as shown in U.S. Pat. No. 4,197,944; on catheters as shown in U.S. Pat. No. 4,178,735; on esophageal probes as shown in U.S. Pat. No. 4,349,031; on laryngoscope blades as shown in U.S. Pat. No. 3,426,749 and on endoscopes as shown in U.S. Pat. Nos. 4,991,565 and 4,974,580.
Except for the endoscope sheaths of U.S. Pat. Nos. 4,991,565 and 4,974,580, the previous patents for disposable sheath devices are not used with medical devices that require visual examination through the sheath.
Although the endoscope sheath of U.S. Pat. No. 4,991,565 permits visual examination through the sheath, it does not address the problem of visual acuity through the sheath. The known sheath also supports an air tube, a water tube and a suction tube and is thus a relatively complex and expensive sheath. In addition, the known sheath must be custom-fitted to the endoscope in an elongated groove formed along the barrel of the endoscope.
U.S. Pat. No. 4,974,580 requires a custom fitted sheath having a glass lens and an enlarged mounting structure to engage a body portion of the endoscope that supports a video camera.
It is thus desirable to provide a relatively inexpensive disposable sheath for an endoscope that provides optimum visual acuity through the sheath.